Microprocessors today generate large amounts of heat that needs to be dispersed. Today there are currently multiple methods of dispersing that heat. There are currently many different methods to use in cooling.
Fan cooling being the standard, which simply has a finned heatsink of aluminum or copper with the possibility of in-fused heatpipes and a fan blowing on top of it. That would keep the temperature to around 33-60° C.
Then, there is the water cooling method that uses simply a pump pushing water from a tube into a maze block which is put onto the microprocessor. Then, the water is pushed into a radiator where it is cooled with a fan and then pumped back into the reservoir from which it is pumped back again into the maze block, and so it repeats. This keeps the microprocessor at around room temperature or at least at the admitted temperature range of 33-60° C.
Also, phase change cooling (as called the current market) is known in prior art, which can go down to around −40° C. through −60° C. on current commercial products. Phase change cooling utilizes the use of a refrigerant from Freon gas to Propane, compresses it, and cools it to transform the gas into a liquid, thus bringing down the temperature of the refrigerant significantly. Then, the refrigerant is poured through a maze evaporator block in which it contacts the heat from the CPU and evaporates in thus dispersing the heat. The maximum lowest a phase change cooler has ever gotten was at −159° C. and had three stages using 3 gases with the final gas being ethylene. But it requires over 2500 W of power and was very large with an unstable design in which the temperature cannot be controlled very efficiently, if it was controlled at all. Then finally, there is liquid nitrogen cooling in which liquid nitrogen is simply poured into an open evaporator and placed onto the microprocessor.
The previous three methods mentioned are cryogenic cooling. Then of course there are the industrial cryogenic cooling methods of the use of phase change in liquid Helium, liquid Nitrogen, finally with liquid Hydrogen. Those methods are purely industrial or laboratory used because they require a 3-phase power connection and use multiple kilowatts at that, require other cooling devices to cool them, and a Stirling Cycle Cryocooler (known as a liquefier in this form of use) or a expensive variation to be used. Not only that, but some of them require a vacuum around the object cooled. Finally, because they cannot disperse enough heat over an area of 50 W while making a large usually 250 W version to be extremely expensive and even more complex.
For example, U.S. Pat. No. 5,647,217 granted to L. B. Penswick and R. E. Neely gives the general design of the Stirling Cycle Cryogenic Cooler. That consists of a compressor piston inside a cylinder and an expansion piston within a cylinder and a driving mechanism such as a motor. Then this functions as a reciprocating motion compressor which can be expanded as shown then the stated patent into a cryocooler.
A newer option is a Vortex tube but that requires a high power air compressor with a large supply of air. Thus the 3-phase power requirement is also needed. And though the compressor may be several hundred kg in weight, the cooling is simply a much colder fan blowing as around −30° C. at it's lowest. The idea behind is a good because the design can be very small, but the machinery required to run it for all it's inferior cooling power to water cooling and Peltiers (thermoelectric coolers), any other cryocooler make it not very efficient to use in most situations.
There is of course the, older Joule-Thomson cryostat which has a “Joule-Thompson Valve”, but again you need a constant supply of high pressure gas and you need a large amount of the gas used. Thus, that requires a pump, a large compressor, a heat exchanger to cool the compressor, a multi-hundred gallon if not more pressurized gas tank, and still the 3-phase power requirement which is only available in industrial zone.
The top cooling is using lasers to slow down single atoms to temperatures very near absolute zero thus resulting into a Bose-Einstein Condensate (BEC). This is the coldest object in the Universe but is only the size of a few atoms and must be kept in a magnetic field and in a vacuum to make this. This is only possible in laboratories and under certain machinery and conditions not to mention the cost of millions of dollars for the equipment need. The BEC also is too small to cool an object with a mass slightly greater then itself. Thus this cannot be used in any application where extreme cooling is needed other then to be used in experiments.
But there is no use for a cryocooler to be used on microprocessors other then on super computers unless two more factors are taken into account. A microprocessor or more specifically a computer's CPU can be “over-clocked” or have it's voltage raised to force more electrical current through it's transistors thus effectively allow raising the processor frequency and so increasing the operational speed. But the extra current and voltage through such a small space would create more heat which would need to be dispersed or otherwise it will melt the transistors which range from 30-130 nanometers in thickness. The higher the current the more heat and thus the more cooling needed.
The second factor is superconduction which is only available under 2 Kelvin and that is with only liquid Helium and liquid Hydrogen The benefit of superconduction is that the resistance in the transistors is significantly lowered thus allowing the electrical current to achieve it's maximum transfer speed through the microprocessor. The performance boost is to be an added 10% of the previous speed. But superconduction in CPU's is purely theoretical until scientific progression in superconducting materials.